Significance of spontaneous apoptosis during colorectal tumorigenesis

To determine if apoptosis is involved in colorectal tumorigenesis and its progression, colorectal adenomas (n = 63), carcinomas (n = 49), and normal mucosa were investigated by using in situ end-labeling (TUNEL) method. The expression of Ki-67 was also analyzed immunohistochemically. TUNEL labeling index (TLI) and Ki-67 labeling index (KLI) were determined. TLI/KLI was significantly higher in the adenomas of small size and/or of low and middle grade atypia than those of large size and/or of high grade atypia. No difference was observed in the indices between adenomas and carcinomas and among the cancer groups classified on the basis of their clinicopathological features. The results indicate that the reduction of susceptibility to apoptosis plays an important role in the early stage of the adenoma-carcinoma sequence. Apoptosis can explain the enormous cell loss thought to exist in normal colorectal mucosa and in the tumor growth process. © 1996 Wiley-Liss, Inc.     

Ultrastructural differences among afferent synapses on cochlear hair cells: Correlations with spontaneous discharge rate

The major class of cochlear afferent fibers, the type-I or radial-fiber (RF) population, has been subdivided into three functional groups according to spontaneous discharge rate (SR): those with low SR have the highest acoustic thresholds, high SR fibers have the lowest thresholds and medium SR fibers are of intermediate sensitivity (Liberman [1978] J. Acoust. Soc. Amer. 63:442–455). Existing evidence from intracellular labeling studies at the light microscopic level (Liberman [1982a] Science 216:1239–1241) suggests that a single cochlear inner hair cell makes synaptic contact with representatives of all three functional groups; however, low and medium SR fibers are spatially segregated from high SR fibers around the hair cell circumference, and low and medium SR fibers are smaller in caliber than those with high SR. The present study extends to the ultrastructural level the structure-function correlations available via intracellular labeling. Analysis is based on serial section reconstruction of the synaptic contacts between 11 radial fibers of known SR and their target hair cells. Results suggest systematic differences in synaptic ultrastructure among fibers of the three SR groups: with decreasing SR, the size and complexity of the synaptic body (a presynaptic specialization characteristic of the peripheral afferent synapses in all hair cell systems and some other peripheral receptors) tend to increase, as does the associated number of synaptic vesicles. The possible functional significance of these trends is discussed in the context of other known structural and functional differences among the three SR groups. © 1996 Wiley-Liss, Inc.     

Synaptic target selectivity and input of GABAergic basket and bistratified interneurons in the CA1 area of the rat hippocampus

To assess the position of interneurons in the hippocampal network, fast spiking cells were recorded intracellularly in vitro and filled with biocytin. Sixteen non-principal cells were selected on the basis of 1) cell bodies located in the pyramidal layer and in the middle of the slice, 2) extensive labeling of their axons, and 3) a branching pattern of the axon indicating that they were not axo-axonic cells. Examination of their efferent synapses (n = 400) demonstrated that the cells made synapses on cell bodies, dendritic shafts, spines, and axon initial segments (AIS). Statistical analysis of the distribution of different postsynaptic elements, together with published data (n = 288) for 12 similar cells, showed that the interneurons were heterogeneous with regard to the frequency of synapses given to different parts of pyramidal cells. When the cells were grouped according to whether they had less or more than 40% somatic synaptic targets, each population appeared homogeneous. The population (n = 19) innervating a high proportion of somata (53 ± 10%, SD) corresponds to basket cells. They also form synapses with proximal dendrites (44 ± 12%) and rarely with AISs and spines. One well-filled basket cell had 8,859 boutons within the slice, covering an area of 0.331 mm² of pyramidal layer tangentially and containing 7,150 pyramidal cells, 933 (13%) of which were calculated to be innervated, assuming that each pyramidal cell received nine to ten synapses. It was extrapolated that the intact axon probably had about 10,800 boutons innervating 1,140 pyramids. The proportion of innervated pyramidal cells decreased from 28% in the middle to 4% at the edge of the axonal field. The other group of neurons, the bistratified cells (n = 9), showed a preference for dendritic shafts (79 ± 8%) and spines (17 ± 8%) as synaptic targets, rarely terminating on somata (4 ± 8%). Their axonal field was significantly larger (1,250 ± 180 μm) in the medio-lateral direction than that of basket cells (760 ± 130 μm). The axon terminals of bistratified cells were smaller than those of basket cells. Furthermore, in contrast to bistratified cells, basket cells had a significant proportion of dendrites in stratum lacunosum-moleculare suggesting a direct entorhinal input. The results define two distinct types of GABAergic neuron innervating pyramidal cells in a spatially segregated manner and predict different functions for the two inputs. The perisomatic termination of basket cells is suited for the synchronization of a subset of pyramidal cells that they select from the population within their axonal field, whereas the termination of bistratified cells in conjunction with Schaffer collateral/commissural terminals may govern the timing of CA3 input and/or voltage-dependent conductances in the dendrites. © 1996 Wiley-Liss, Inc.     

Variations in bovine milk oligosaccharides after calving using p-aminobenzoic ethyl ester closed-ring labeling and negative ion electrospray LC/MS/MS

A strategy was proposed to analyze bovine milk oligosaccharides using p-aminobenzoic ethyl ester (ABEE) closed-ring labeling and C18 capillary liquid chromatography negative ion electrospray tandem mass spectrometry. Linkage specific fragment ions were used to identify oligosaccharide isomers. By constructing the mass chromatograms using linkage specific fragment ions, isomers were differentiated based on m/z values as well as temporal separation provided by liquid chromatography. In addition to disialyllactose and the single isomer lacto-N-neohexaose, four pairs of linkage isomers including 3′/6′-sialyllactose (3′/6′-SL), 3′/6′-sialyllactosamine (3′/6′-SLN), 3′/6′-sialylgalactosyl-lactose (3′/6′-SGL), and lacto-N-tetraose/lacto-N-neotetraose (LNT/LNnT) in bovine milk were investigated. Variations of bovine milk oligosaccharides in a lactation period of 72 h after calving were studied. Sialylated oligosaccharide was found to be distinctively more abundant in milk of the first 24 h, decreasing in successive milkings. For the first time, the variation of lacto-N-tetraose in bovine milk was reported.     

Accelerated iTBS treatment applied to the left DLPFC in depressed patients results in a rapid volume increase in the left hippocampal dentate gyrus,not driven by brain perfusion

BackgroundAccelerated intermittent Theta Burst Stimulation (aiTBS) has been shown to be an effective antidepressant treatment. Although neurobiological changes shortly after this intervention have been reported, whether aiTBS results in structural brain changes must still be determined. Furthermore, it possible that rapid volumetric changes are driven by factors other than neurotrophic processes.ObjectivesWe examined whether possible grey matter volumetric (GMV) increases after aiTBS treatment could be driven by increased brain perfusion, measured by Arterial Spin Labeling (ASL).Methods46 treatment-resistant depressed patients were randomized to receive 20 sessions of active or sham iTBS applied to the left dorsolateral prefrontal cortex. All sessions were delivered over 4 days at 5 sessions per day (trial registration: http://clinicaltrials.gov/show/NCT01832805). Patients were scanned the day before starting stimulation and three days after aiTBS.ResultsThere was a significant cluster of increased left hippocampal GMV in the dentate gyrus related to HRSD changes after active aiTBS, but not after sham stimulation. These GMV increases became more pronounced when accounting for changes in cerebral perfusion.ConclusionsActive, but not sham, aiTBS, resulted in acute volumetric changes in parts of the left dentate gyrus, suggesting a connection with adult neurogenesis. Furthermore, taking cerebral perfusion measurements into account impacts on detection of the GMV changes. Whether these hippocampal volumetric changes produced by active aiTBS are necessary for long-term clinical improvement remains to be determined.     

Organization of ventral tegmental area cells projecting to the occipital cortex and forebrain in the rat

Our horseradish peroxidase retrograde tracing study revealed a specific subpopulation of ventral tegmental area (VTA) neurons that send axons to the occipital cortex in the rat. A fluorescent retrograde tracing study demonstrated that neuronal populations in the VTA projecting to the occipital cortex are distributed in a manner separate from those projecting to forebrain structures such as the frontal/anterior cingulate cortices and nucleus accumbens. The scarcity of collateral projections from the VTA contrasts with the extensive collateralization of projection neurons in the substantia nigra pars compacta. Projections to the occipital cortex may define the distribution of cells comprising the VTA and thus the clear hodological separation of the A9 and A10 dopamine cell groups.     

动脉自旋标记技术在脑缺血影像诊断中的临床初步应用

目的评价动脉自旋标记技术(ASL)在慢性脑缺血灌注分析中的临床应用价值。方法健康志愿者5例,临床表现为慢性颈内动脉系统缺血症状的患者11例。使用3.0TMR成像系统对受试者除行常规MR平扫外,还行Q2TIPS的ASL扫描。观察所得相对局部脑血流量(rCBF)彩图有无灌注减低区,对灌注减低区采用注量变化程度来显示灌注变化的情况。结果在健康志愿者,ASL技术可清楚显示脑灰质、白质及深部核团的不同血流分布,灰质血流量明显高于白质。在11例颈内动脉系统脑缺血患者中3例临床表现为TIA的患者,其ASL灌注图显示双侧脑血流分布对称,无rCBF减低区,余8例患者共发现17个区域的rCBF较健侧明显减低。结论ASL可用于脑缺血患者的脑组织灌注评估。     

Ammonium accumulation and chemokine decrease in culture media of Gcdh−/− 3D reaggregated brain cell cultures

Glutaric Aciduria type I (GA-I) is caused by mutations in the GCDH gene. Its deficiency results in accumulation of the key metabolites glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA) in body tissues and fluids. Present knowledge on the neuropathogenesis of GA-I suggests that GA and 3-OHGA have toxic properties on the developing brain.We analyzed morphological and biochemical features of 3D brain cell aggregates issued from Gcdh^?/? mice at two different developmental stages, day-in-vitro (DIV) 8 and 14, corresponding to the neonatal period and early childhood. We also induced a metabolic stress by exposing the aggregates to 10 mM l-lysine (Lys).Significant amounts of GA and 3-OHGA were detected in Gcdh^?/? aggregates and their culture media. Ammonium was significantly increased in culture media of Gcdh^?/? aggregates at the early developmental stage. Concentrations of GA, 3-OHGA and ammonium increased significantly after exposure to Lys. Gcdh^?/? aggregates manifested morphological alterations of all brain cell types at DIV 8 while at DIV 14 they were only visible after exposure to Lys. Several chemokine levels were significantly decreased in culture media of Gcdh^?/? aggregates at DIV 14 and after exposure to Lys at DIV 8.This new in vitro model for brain damage in GA-I mimics well in vivo conditions. As seen previously in WT aggregates exposed to 3-OHGA, we confirmed a significant ammonium production by immature Gcdh^?/? brain cells. We described for the first time a decrease of chemokines in Gcdh^?/? culture media which might contribute to brain cell injury in GA-I.     

Potential function of TGF-β isoforms in maturation-stage ameloblasts

Objectives

To investigate potential functions of transforming growth factor-beta (TGF-β) isoforms in maturation-stage ameloblasts during amelogenesis.

氯化锰标记前列腺癌细胞株的体外MRI研究

目的 初步探索使用氯化锰（MnCl2）标记前列腺癌细胞株（PC-3）行体外MRI的可行性和安全性.方法 将PC-3进行复苏、培养和扩增.在细胞培养箱中,PC-3与8组含不同MnCl2浓度的F-12 HAM＇S培养基共同培养1h,收集已标记的PC-3并行MRI.另对不同细胞数量级和不同时间点的MnCl2标记的PC-3行MRI.用含维拉帕米的培养基培养MnCl2标记的PC-3 4 h,在不同时间点取标记后的PC-3行MRI.用WST-8法测定氯化锰标记的PC-3活性.结果 MnCl2标记的PC-3在T1WI显示为高信号,其信号强度与未标记的PC-3形成明显差异（P＜0.01）,以1.0 mmol /L MnCl2为标记浓度时信号强度最强.1.0mmol/L MnCl2标记的PC-3在细胞数量为0.5×106时可呈高信号.在体外培养的条件下,标记后24 h的PC-3信号强度明显下降,标记后72 h基本恢复至未标记的PC-3信号强度水平.维拉帕米可延长MnCl2标记的PC-3有效成像时间至72 h.标记后4 h,除0.1 mmol/L MnCl2对PC-3的活性没有影响（P ＞ 0.05）外,其余各浓度组（＞ 0.1mmol/L）的MnCl2对PC-3的活性均有不同程度的影响（P ＜ 0.05）;标记后24h,0.5 ～ 1.0 mmol/L MnCl2对细胞的活性影响不明显（P ＞ 0.05）.结论 MnCl2可以有效标记PC-3,并能在T1WI以高信号成像且具有一定灵敏度.在浓度低于或等于1.0 mmol/L时,标记PC-3有一定的安全性,但标记维持时间较短.钙离子通道阻滞剂（维拉帕米）可适当延长PC-3的MnCl2标记维持时间.